Spatial light modulators (SLMS) have numerous applications in the areas of optical information processing, projection displays, video and graphics monitors, televisions, and electrophotographic printing. Reflective SLMs are devices that modulate incident light in a spatial pattern to reflect an image corresponding to an electrical or optical input. The incident light may be modulated in phase, intensity, polarization, or deflection direction. A reflective SLM is typically comprised of an area or two-dimensional array of addressable picture elements (pixels) capable of reflecting incident lights. Source pixel data is first processed by an associated control circuit, then loaded into the pixel array, one frame at a time.
SLM devices are typically fabricated by defining moveable reflective elements. These moveable reflective elements are typically fabricated by etching along a periphery, in order to release them from the surrounding material.
Where the moveable reflective elements are formed from single crystal silicon, a plasma etching step in an ambient including oxygen, has conventionally been employed for this mirror releasing process. Use, however, of such oxygen-containing plasmas to release the moveable reflecting elements, offers certain disadvantages. For example, etching in an oxygen ambient may create residues that can undesirably affect the mechanical and optical properties of the resulting device. In addition, etching in an oxygen plasma may undesirably result in physical damage to the thin mirror structures due to plasma charging.
Accordingly, there is a need in the art for improved methods of fabricating SLM devices.